U.S. patent application number 11/818839 was filed with the patent office on 2008-12-18 for heatsink having an internal plenum.
Invention is credited to Kurt F. O'Connor.
Application Number | 20080310116 11/818839 |
Document ID | / |
Family ID | 39800538 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080310116 |
Kind Code |
A1 |
O'Connor; Kurt F. |
December 18, 2008 |
Heatsink having an internal plenum
Abstract
A heatsink for conducting heat away from an electric module in
thermal contact with the heatsink includes at least a first
heatsink member joined to at least a second heatsink member by a
weld joint to define a heatsink having an internal plenum. By
replacing conventional adhesive and fastening means used for
sealing heatsink members together with a welded joint, a more
durable and reliable sealed plenum is obtained. In a preferred
aspect, the weld joint is created using a friction stir welding
technique.
Inventors: |
O'Connor; Kurt F.; (Carmel,
IN) |
Correspondence
Address: |
DELPHI TECHNOLOGIES, INC.
M/C 480-410-202, PO BOX 5052
TROY
MI
48007
US
|
Family ID: |
39800538 |
Appl. No.: |
11/818839 |
Filed: |
June 15, 2007 |
Current U.S.
Class: |
361/707 ;
257/E23.098; 29/890.054 |
Current CPC
Class: |
Y10T 29/49393 20150115;
H01L 2924/0002 20130101; H01L 23/473 20130101; H01L 2924/0002
20130101; H01L 2924/00 20130101; H01L 2924/09701 20130101 |
Class at
Publication: |
361/707 ;
29/890.054 |
International
Class: |
H05K 7/20 20060101
H05K007/20; B23P 15/26 20060101 B23P015/26 |
Claims
1. A heatsink for conducting heat away from an electronic module,
comprising: at least a first heatsink member joined to at least a
second heatsink member by a weld joint to define a heatsink having
an internal plenum, the weld joint having a mechanical strength
property that is greater than the mechanical strength property of a
thermal weld joint; and at least one electronic module in thermal
contact with the heatsink.
2. The heatsink of claim 1, wherein the heatsink members are
comprised of a material having a thermal conductivity of at least
10 watts per meter per degree Kelvin.
3. The heatsink of claim 1, wherein the heatsink members are
comprised of a material having a thermal conductivity of at least
100 watts per meter per degree Kelvin.
4. The heatsink of claim 1, wherein the heatsink members are
comprised of aluminum.
5. The heatsink of claim 1, wherein the heatsink members are
aluminum castings.
6. The heatsink of claim 1, wherein the weld joint is produced by
friction stir welding.
7. A process for making a heatsink for conducting heat away from an
electronic module in thermal contact with the heatsink, comprising:
providing at least a first heatsink member and a second heatsink
member that are configured to be joined along mating edges to
define a heatsink having an internal plenum; and welding the
heatsink members together along the mating edges to form a heatsink
having an internal plenum.
8. The process of claim 7, wherein the heatsink members are
comprised of a material having a thermal conductivity of at least
10 watts per meter per degree Kelvin.
9. The process of claim 7, wherein the heatsink members are
comprised of a material having a thermal conductivity of at least
100 watts per meter per degree Kelvin.
10. The process of claim 7, wherein the heatsink members are
comprised of aluminum.
11. The process of claim 7, wherein the heatsink members are
aluminum castings.
12. The process of claim 7, wherein the weld joint is produced by
friction stir welding.
13. A heatsink for conducting heat away from an electronic module,
comprising: at least a first heatsink member joined to at least a
second heatsink member by a weld joint to define a heatsink having
an internal plenum, the weld joint having a grain structure that is
finer than the grain structure of a thermal weld joint; and at
least one electronic module in thermal contact with the
heatsink.
14. The heatsink of claim 13, wherein the heatsink members are
comprised of a material having a thermal conductivity of at least
10 watts per meter per degree Kelvin.
15. The heatsink of claim 13, wherein the heatsink members are
comprised of a material having a thermal conductivity of at least
100 watts per meter per degree Kelvin.
16. The heatsink of claim 13, wherein the heatsink members are
comprised of aluminum.
17. The heatsink of claim 13, wherein the heatsink members are
aluminum castings.
18. The heatsink of claim 13, wherein the weld joint is produced by
friction stir welding.
Description
TECHNICAL FIELD
[0001] This invention relates to cooling of electronic modules that
generate a high amount of heat, and more particularly to the use of
heatsinks having an internal plenum for circulating a fluid medium
to cool an electronic module.
BACKGROUND OF THE INVENTION
[0002] For an electronic module that consumes a high amount of
power, and therefore, generates a large amount of heat that must be
dissipated to prevent overheating of sensitive components of the
electronic module, means are provided to move heat away from the
electronic module. In certain cases, it is possible to remove a
sufficient amount of heat to prevent damage and/or malfunction of
the electronic module by placing a thermally conductive heatsink
structure in contact with the electronic module. The heatsink may
include cooling fins to increase the surface area available for
convective heat transfer from the heatsink to the surrounding air.
A fan may also be employed to move air past the cooling fins and
further enhance convective heat transfer. However, electronic
modules having very high levels of power consumption which generate
more heat than can be effectively removed by a solid heatsink and a
fan are becoming more common. For these devices more efficient heat
transfer means must be employed. Typically, these means take the
form of heatsinks which define an internal plenum for distributing
and/or circulating a cooling medium, which may be either a liquid
or a gas.
[0003] Conventional heatsinks having an internal plenum for
distributing and/or circulating a cooling medium typically comprise
at least two castings that are sealingly mated together to form an
internal cavity. The individual castings are generally sealingly
attached to one another using an adhesive sealant and mechanical
fasteners. These conventional sealing means are subject to latent
defects and deterioration that can result in failure of the seal
and ultimately failure of the electronic module.
SUMMARY OF THE INVENTION
[0004] The invention provides a heatsink having an internal plenum
for distributing and/or circulating a cooling medium which employs
an improved means for sealingly mating together at least a first
heatsink member to at least a second heatsink member, which is less
susceptible to latent defect and deterioration.
[0005] In accordance with an aspect of the invention, a heatsink
for conducting heat away from an electronic module in thermal
contact with the heatsink includes at least a first heatsink member
joined to at least a second heatsink member by a weld joint. In
accordance with a preferred aspect of the invention, the weld joint
is generated using a friction stir welding technique.
[0006] In accordance with another aspect to the invention, there is
provided a process for making a heatsink for conducing heat away
from an electronic module in thermal contact with the heatsink. The
process includes steps of providing at least a first heatsink
member and a second heatsink member that are configured to be
joined along mating edges to define a heatsink having an internal
plenum, and welding the heatsink members together along the mating
edges to form a heatsink having the internal plenum. In accordance
with a preferred aspect of the invention, the welding step is
achieved using a friction stir welding technique.
[0007] In accordance with the disclosed heatsink and method of
making same, the weld joint provides a seal along the mating edges
of the heatsink members that is extremely durable and reliable.
[0008] These and other features, advantages and objects of the
present invention will be further understood and appreciated by
those skilled in the art by reference to the following
specification, claims and appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will now be described, by way of
example, with reference to the accompanying drawings, in which:
[0010] FIG. 1 is a cross-sectional view of a heatsink having an
internal plenum or cavity for circulating and/or distributing a
fluid medium to convectively remove heat from the heatsink.
[0011] FIG. 2 is a top plan view of a fluid medium distribution
plate located in the heatsink shown in FIG. 1.
[0012] FIG. 3 is a perspective view showing the components of the
heatsink of FIGS. 1 and 2 prior to assembly.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Shown in FIG. 1 is a heatsink 10 in accordance with the
invention having a first heatsink member 12 joined to a second
heatsink member 14 by a weld joint 16. In the illustrated
embodiment, as shown in FIG. 3, the first heatsink member 12 has an
open box-like shape or configuration defined by opposite sidewalls
18, 19, opposite end walls 20, 21, and roof 22. Sidewalls 18, 19
and end walls 20, 21 define a ledge or step 24. An optional cooling
medium distribution plate 26 is retained between ledge 24 and
second heatsink member 14. A cooling medium inlet port 28 and a
cooling medium outlet port 30 are defined through end wall 20.
Electronic modules 32, 33 are positioned on heatsink 10 in thermal
contact with the exterior surface 31 of roof 22. The expression "in
thermal contact" as used herein means that heat can be conducted
from electronic modules 32, 33 through roof 22 to internal surface
36 of roof 22, either directly or through a material interposed
between roof 22 and modules 32, 33, such as a thermally conductive
adhesive.
[0014] The heat is convectively transferred from heatsink 10
through outlet port 30 by a heat transfer fluid or cooling medium
passing through cavity 38 and contacting surface 36. In use,
conduits such as pipes or tubing will be connected to the inlet
port 28 and outlet port 30 to supply cool medium to the heatsink
plenum and to typically return heated heat transfer medium to a
radiator where it is cooled for recirculation to the heatsink
plenum.
[0015] The electrical modules (e.g., 32, 33) can be generally any
electrically powered device that generates heat and requires
cooling during its operation.
[0016] In the illustrated embodiment, optional cooling medium
distribution plate 26 is preferably used to redirect the flow of
the cooling medium through apertures 40 in a direction generally
perpendicular to surface 36 so that the fluid impinges directly
against surface 36 to enhance convective heat transfer and reduce
or eliminate stagnant pockets of cooling medium within cavity 38.
The expression "plenum" as used herein means a cavity defined
within the heatsink, or a portion of a cavity defined within a
heatsink that is used for distributing flow of the cooling medium
along internal surfaces of the heatsink.
[0017] The cooling medium may comprise generally any suitable
liquid (such as water) or gas (such as air) that may be effectively
utilized for convective heat transfer.
[0018] Heatsink members 12, 14 are made of a weldable material that
has a relatively high thermal conductivity, typically at least 10
watts per meter per degree Kelvin (Wm.sup.-1K.sup.-1), and more
preferably at least 100 watts per meter per degree Kelvin. Suitable
materials for heatsink members 12, 14 are weldable metals or metal
alloys, more preferably weldable metals or metal alloys that are
resistant to corrosion, such as aluminum, aluminum alloys, copper,
copper alloys, magnesium, magnesium alloys, and stainless steel.
Although various other materials may be utilized, most preferably,
heatsink members 12, 14 are comprised of aluminum because of its
relatively high thermal conductivity, low cost, and the ease by
which it can be cast and/or machined. Cooling medium distribution
plate 26 may be fabricated from generally any material having
suitable resistance to the selected cooling medium, and may be made
of various metals or metal alloys, plastics, glass, or ceramic
materials.
[0019] In a preferred embodiment, heating members 12, 14 are joined
and sealed together by a weld joint 16 that is produced by a
friction stir welding technique. In friction stir welding, a tool
with a probe attached to its tip is rotated at a high speed while
being pushed against abutting sections of the pieces of metal to be
welded together. The downward pressure applied to the probe and
transferred to the abutting sections of the metal pieces creates
friction heat between the probe and the metal causing the metal to
become plasticized. The circular movement of the probe mixes the
metals from the two pieces (which may be comprised of the same or
different metals or alloys) together to form a homogenous bond
joint. As the friction stir equipment senses that the material has
been plasticized, it progresses along a pre-programmed weld path.
Friction stir welding has several advantages over other welding
techniques. First, it creates a hermetic seal between the joined
pieces, and second, unlike with fusion welding techniques, weld
joints produced by friction stir welding techniques have excellent
mechanical properties regardless of whether the joined pieces are
composed of the same or different metals or metal alloys. The
strong and durable weld joint between the heatsink members
eliminates the need for adhesives and mechanical fasteners, thereby
eliminating the need for adhesive dispensing equipment and
equipment or labor needed for mechanical fastening. Friction stir
welding also produces a reliable weld joint that is not susceptible
to failure, and which provides improved electromagnetic
compatibility. In fact, the high reliability of the weld joint
produced by friction stir welding is expected to eliminate the need
for leak testing after assembly.
[0020] The weld joint formed by friction stir welding has a grain
structure that is smaller (finer) and a mechanical strength
property that is greater than that of a weld joint formed using a
thermal welding technique (e.g., MIG, TIG, arc welding, acetylene
welding).
[0021] Welding of plenum member provides a conductive path for
ground and improved resistance to electromagnetic interference.
[0022] It will be understood by those who practice the invention
and those skilled in the art that various modifications and
improvements may be made to the invention without departing from
the spirit of the disclosed concept. The scope of protection
afforded is to be determined by the claims and by the breadth of
interpretation allowed by law.
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